Investigation of the specific impact of aging on the pituitary secretion of LH (luteinizing hormone). With aging, the amount of testosterone secreted by the testicles diminishes, even amoung those men who have no known health disorders, ingest no medicine, don't smoke, and don't ingest alcoholic beverages. Testosterone availability is even lower amoung men with chronic diseases. Testerone deficiency can be associated with decreased muscle mass and strength, diminished bone mineral density, hip fracture, and loss of sexual interest. Hyperandrogenism (deficiency of masculating substances), has also been associated with coronary artery disease, and impaired spatial cognition. The exact relationship between diminished testosterone availability and frailty, disability, or death, has not been well studied, but the associations are likely. This randomized, controlled trial will involve 40 male subjects of any race, ages 20-40 and 60-80, who are entirely healthy, on no medications, on no hormones, have had no chronic or acute illness within four weeks prior to entering the study. There will also be no mental or emotional illness, no tobacco use, and no daily or binge alcohol use. There will be no transmeridian travel within three weeks. Weight will be within 20% of ideal. All subjects will have six admissions to the General Clinical Research Clinic. During each visit, subjects will receive ketoconazole and dexamethasone along with a snack. Half of the subjects will receive testosterone, also. All subjects will receive the two medications again at 8:00am. Blood samples will be obtained every ten minutes from 8:00am to 1:00pm. At 10:00 am, subjects will receive GnRH. A different dose will be given on each of the six admissions. At 1:00, all subjects will receive dexamethasone and then eat lunch.